Can't solve child parent association in cakephp 3 - php

Question

I have table with a parent child relationship with itself:
mysql> desc features;
+---------------------+-------------+------+-----+-------------------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------------------+-------------+------+-----+-------------------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| featureID | varchar(45) | NO | | NULL | |
| probeID | int(11) | YES | | NULL | |
| shortName | varchar(45) | NO | | NA | |
| start | int(11) | NO | | NULL | |
| stop | int(11) | NO | | NULL | |
| strand | int(11) | NO | | NULL | |
| curatedManually | varchar(45) | NO | | NA | |
| created | timestamp | NO | | CURRENT_TIMESTAMP | |
| descriptions_id | int(11) | YES | MUL | NULL | |
| features_types_id | int(11) | NO | MUL | NULL | |
| chromosomes_id | int(11) | NO | MUL | NULL | |
| species_id | int(11) | NO | MUL | NULL | |
| strains_id | int(11) | NO | MUL | NULL | |
| parents_features_id | int(11) | YES | MUL | NULL | |
+---------------------+-------------+------+-----+-------------------+----------------+
The according fields are parents_features_id and id, because a feature can have "child"-features or "parent"-features. There is a foreign key relationship established with this fields.
KEY `fk_features_Features1_idx` (`parents_features_id`),
CONSTRAINT `fk_features_Features1` FOREIGN KEY (`parents_features_id`) REFERENCES `features` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION,
I used "cake bake all features" to create all necessary models, controllers etc.
When I open the features page I only get the error message "Features is not associated with ParentsFeatures"
I tried to solve it by exchanging the automatic original code
$this->belongsTo('Features', [
'foreignKey' => 'parents_features_id'
in Model/Table/FeaturesTable.php for this relationship by the following code:
$this->belongsTo('ParentsFeatures', [
'className' => 'Features',
'foreignKey' => 'parents_features_id'
]);
$this->hasMany('ChildFeatures', [
'className' => 'Features',
'foreignKey' => 'parents_features_id'
But than I get the error message "Features is not associated with Features"
I am a little bit stuck here and would really appreciate any help to solve this.
all the best
Nadine

Answer 1

Making changes to the associations in your table will not change the way the baked controllers will query the data, you'll have to change them too, or re-bake your code.
However, this will never bake correctly unless you start following the conventions, that is name the foreign key column parent_id, only then bake will be able to create the proper associations (which will be named ParentFeatures and ChildFeatures), and while you're at it, consider changing the other column names too (lowercase underscored).
That being said, there might be a bug that occours somewhere between renaming indexes, creating and deleting foreign key constraints, etc (can't pinpoint it down), which then causes wrong association names used for contain in the find() calls of the controller actions, ie bake will generate something like
'contain' => ['Features']
instead of
'contain' => ['ParentFeatures']
which it used for the association in the baked table class.
However I'm not being able to reproduce it reliably right now. In case this is what you are experiencing, you might want to report this as an issue over at GitHub.
In case re-baking doesn't fix it, manually check the find() calls in your controller actions and change the contained association to ParentFeatures.